“We’re going to die, we’re actually going to die,” the person filming is heard saying.
The bus then crashed through barriers and into the river as the students on board from Barton Peveril Sixth Form College screamed.
The driver and one passenger, who were taken to hospital, are in a “serious but not life-threatening” condition, Hampshire Constabulary said.
Freddie Sampson, an 18-year-old student on board, said the driver had “lost control” after crashing into a lamp-post.
He told BBC News: “We ran into a lamp-post and the whole windscreen shattered”.
“It was like we couldn’t stop and had to weave through traffic, trying not to hit any cars and then the bus driver lost control. We went flying into the river.”
Sampson said that one passenger had been “quite badly injured on their head” and that others were treated for cuts.
Bruno Aguiar, an electrician who lives in Eastleigh, was first on the scene. He was on his way to work when his van was almost struck by the bus.
Dashcam footage from his van shows the moment the bus crashed into the river.
Aguiar said: “I saw the bus coming really fast. I swerved to the pavement, and the bus came into the middle of both lanes.
“It hit a red Corsa from a driving school and then went into the river. I came out of my van to see what had happened.
“I went to check on the driver, and he was asking for an ambulance. I saw it was full of children.”
Bruno pulled a ladder from his van to help bring the students to safety. He added that another man wearing a Bluestar uniform, believed to have been passing by, was “really quick to help” in getting the children off the bus.
Aguiar said: “I wasn’t thinking clearly. The children were all panicked. A child doesn’t think; they wait for help.
“They were bleeding from the head and from the arms. I think it was a miracle nobody was more seriously injured.”
South Central Ambulance Service said: “We’re continuing to support and assess patients on scene. All patients have been removed from the bus.
“Three high-priority patients are being taken to hospital. Around 14 with less serious injuries are being treated on scene.”
Bluestar Bus, the bus company involved, said the driver was among those injured, and that there were 19 passengers on board at the time of the crash.
Scott Agass, the father of a 17-year-old on board, said: “He doesn’t really know what happened or what caused it. I suppose it just happened so quick. All he saw was that it crashed and gone in the river.”
Jonathan Holdstock, a resident, said: “It was half 10 when I heard a bunch of sirens. When I heard it was a bus in the river, I didn’t believe it.”
Inspector Andy Tester, of Hampshire Constabulary, said a total of 20 people were on board the bus, 19 of whom were passengers.
He said: “My thoughts are very much with the children and the driver on the bus, who must have had a terrifying experience”.
Tester added that several people, including the driver, were trapped on board when emergency services arrived.
“There were a large number of specialist resources helping to get people out of the bus.
“Some people had got themselves out of the bus, and it was obviously important to us to triage the injured people, to assess the people who were still stuck in the bus, and to make sure we had accounted for everyone.”
Tester added: “We believe that everyone, every passenger on the bus, was a student heading to Barton Peveril college”.
A spokesman for Barton Peveril Sixth Form College said: “We are aware of an incident involving the college 607 bus. College staff are working closely with the police to ensure the safety and wellbeing of all students.”
Richard Tyldsley, the Bluestar general manager, said: “One of our buses, carrying students to Barton Peveril College, was involved in an incident earlier this morning in Bishopstoke Rd, Eastleigh. Reports suggest the bus left the highway and came to rest in a shallow river.
“Our driver and at least two of the passengers have confirmed injuries, and we are awaiting further updates on the status of others on board. At this time, we do not know the circumstances behind this incident and are carrying out an immediate investigation.”
Hampshire Constabulary said the road had been closed and anticipated that would continue to be the case for up to 12 hours.
